Since polymer electrolyte fuel cells have many advantages including a high output, long life, little deterioration caused by starting and stopping, low operating temperature (about 70-80° C.) and unnecessity of precise differential pressure control, polymer electrolyte fuel cells are expected to be useful for a wide range applications including a power source for electric automobiles and distributed power sources for business and domestic uses.
With regard to a solid electrolyte membrane used for producing a polymer electrolyte fuel cell, there is disclosed a technique which forms a thin film of a fluorine-containing solid polymer electrolyte on one face of a stretched porous polytetrafluoroethylene sheet to thereby impart a sealing effect and a thermal and/or mechanical reinforcing effect to the electrolyte thin film (JP-A-8-13179). With regard to the cell structure, there is known a fuel cell membrane electrode assembly in which a groove for passing a gas is cut in a gas diffusion electrode layer (JP-A-8-507402). Further, there is known a structure in which, in order to prevent dislocation between a separation and a packing at the time of stacking, the packing is fit into a concave part of the separator (JP-A-2000-294254).